Hydrofoil flap control system

ABSTRACT

An actuator is connected to a combined hydrofoil and flap, through a bell crank-lever linkage. A change in the foil angle of attack produces a coincident change in the flap angle. Also the bell crank-lever linkage is connected to the actuator to minimize the effect of the flow stream force on the foil and flap by continuously matching the mechanical advantage of the actuator to the force required to move the flap and foil.

United States Patent Whitener 5] Feb.29,1972

[54] HYDROFOIL FLAP CONTROL SYSTEM [72] Inventor: Philip C. Whitener,Seattle, Wash.

[73] Assignee: The United States of America as represented by theSecretary of the Navy [22] Filed: Oct. 16, 1971) [21] App1.No.: 81,301

[52] U.S.Cl. ..114/66.5 11, 114/167 [51] Int. Cl ..B63b U223 [58]FieldofSearch ..114/66.5 H, 167

[56] References Cited UNITED STATES PATENTS 2,996,031 8/1961 Easter ..114/167 3,000,595 9/1961 Dorn ..244/82 3,055,618 9/1962 Bris1awn.......244/87 3,548,774 12/1970 Pease ..1 14/162 Primary Examiner-AndrewH. Farrell AttarneyR. S. Sciascia and Q. E. Hodges [57] AESTRACT Anactuator is connected to a combined hydrofoil and flap, through a bellcrank-lever linkage. A change in the foil angle of attack produces acoincident change in the flap angle. Also the bell crank-lever linkageis connected to the actuator to minimize the effect of the flow streamforce on the foil and flap by continuously matching the mechanicaladvantage of the actuator to the force required to move the flap andfoil.

6 Claims, 2 Drawing Figures PATENTEDFEBZBIQTB I 3,645,223

SHEET 1 [1F 2 INVENTOR. PHIL/P 6. WH/TENEI? ATTORNEY PATENTEDFEBZQ I972SHEET. 2 BF 2 N bFm INVENTOR. PHIL/P C. WH/TENEI? HYDROFOIL FLAP CONTROLSYSTEM DESCRIPTION OF THE PRIOR ART The prior art shows articulatablevanes and aerodynamic control surfaces manipulated through leverlinkages. But linkages employed in the prior art are simple and aresecondary in importance to the functioning of the control surface orvane. These simple linkages provide the minimum of the controlconnection between the driving force and the control vane withoutchanging the mechanical advantage of the actuator.

SUMMARY The present invention refers to a hydrofoil flap combinationwith the flap hinged to the hydrofoil and the hydrofoil rigidly attachedto a movable support arm. The flap is additionally linked to an actuatorand to the hydrofoil support through a bell crank and lever linkage.

A fully submerged hydrofoil requires a large lift coefficient for takeoff. This large lift coefiicient is obtained by increasing the foilangle of attack and using a relatively large flap angle. In thiscondition of large foil angle of attack and large flap angle, the centerof pressure, or the point through which the resultant of the forces areacting on the foil and flap surfaces due to the hydrostatic pressure,produces a relatively larger moment on the foil and flap than thatproduced in a normal flying attitude of a smaller foil angle of attackand smaller flap angle. A much larger actuator force is requiredtherefor to change the angle of the hydrofoil and flap when the angle ofattack of the foil is larger than when the angle of attack is relativelysmaller, as in the case of normal flying attitude.

The purpose of this invention is to link the foil, flap and actuator toincrease the actuator mechanical advantage on the foil when the foil andflap attack angle approaches the maximum, as in takeoff condition, whileallowing a sufiicient mechanical advantage for the actuator acting onthe flap, for a flying attitude angle of attack. Additionally, smallmovements of the foil produce a coincident change in flap angle therebyproducing a larger change in lift coefiicient than would otherwise beinduced by a foil acting alone.

Accordingly, it is one object of this invention to provide a hydrofoiland flap control system which matches the mechanical advantage of anactuator to the force required to move the flap and foil.

A second object of this invention is the hydrofoil and flap controlsystem wherein the flap is linked to the foil to increase the liftproduced by a change of foil angle.

A third object of the invention is a hydrofoil and flap linkagerequiring a lighter weight and smaller actuator.

A fourth object of this invention is a hydrofoil and flap combinationwhere the flap is controlled through the foil linkage and no separateflap control is required.

DESCRIPTION OF THE DRAWINGS FIG. 1 shows the hydrofoil flap controlsystem with the foil and flap set at an intermediate angle of attack.The foil shown in FIG. 1 is at an angle required to maintain the craftin a flying attitude.

FIG. 2 shows the hydrofoil control system of FIG. 1 with the flap andfoil set at an extreme limit of maximum flap and foil angle. This angleof attack is assumed when the craft is starting from a stationaryposition and is being driven toward a flying attitude.

DESCRIPTION OF THE INVENTION Referring now to the figures, wherein likereference characters designate like or corresponding parts, FIG. 1 showsthe hydrofoil flap control system with the flap and foil angle ofattack, 1r, to the flow stream designed to maintain the vessel in aflying attitude. Rigidly attached to a ship structure 1 is a bearing 5.Attached to bearing 5 and pivoting about the center of bearing 5 ishydrofoil strut 3 with foil '7 attached thereto. Bearing 11 is rigidlyattached to foil 7 and pivoting about the axis of bearing 11 is flap 9.A link bar 13 is attached to flap 9 at bearing 15. Bearing 15 is rigidlyattached to flap 9 and link bar 13 pivots about bearing 15. Link bar 13,at the end opposite its attachment point to flap 9, is connected toactuator coupling 19 and to bell crank 21 by hearing 17 connecting linkbar 13, coupling 19 and bell crank 21, permitting the bell crank 21, theactuator coupling 19, and the link bar 13 to pivot about bearing 17.Bell crank 21 is additionally coupled to hydrofoil strut 3 by bearing 23allowing the bell crank and the hydrofoil strut to pivot about bearing23. Bell crank 21 is additionally coupled to support strap 27 by bearing25 allowing strap 27 and bell crank 21 to pivot about bearing 25. Strap27 is additionally attached to ship structure 1, at an end opposite itsattachment point to bell crank 21, by hearing 29. Bearing 29 is rigidlyattached to a structure and allows strut 27 to pivot about bearing 29.Fixed to actuator coupling 19 is actuator arm 31 which is the movablearm portion of hydraulic actuator 33. Hydraulic actuator 33 is attachedto ship structure 1 by bearing 35 allowing actuator 33 to pivot aboutbearing 35.

The set of letters, A-F, each set arranged on an arc passing through thebearings 11, 15, 17, 23 and 25, denote the positions of bearings 11, 15,23 and 25 corresponding to the positions of bearing 17 and actuatorcoupling 19.

OPERATION OF THE DEVICE The angle of the foil and flap to the flowstream is controlled by hydraulic actuator 33. Actuator arm 31,extending coupling 19 and bearing 17 to position A will cause the flapand foil to be at its extreme position of minimum attack angle, 1r, tothe flow stream. At this angle bearings 11, 15, 23 and 25 will bepositioned at A on their respective arcs. At position A, bearings 15, 17and 23 will be substantially on a straight line resulting in asufficiently high-mechanical advantage on the flap and the actuator loadwill be produced almost entirely by the load in strap 27. As actuatorarm 31 is contracted, bearings 17 will move through its respective arcfrom position A through positions B, C, D, E and to its extreme positionF, where the angle of attack of the flap and foil to the flow streamwill be maximum. As the attack angle is increased, bearing 23 will bemoved through its respective are through positions B, C, D and to F,rotating hydrofoil 7 and increasing its angle of attack to a maximum, 1ras shown in FIG. 2. Concurrently, with the movement of bearing 17through its respective arc, actuator 33, acting through coupling 19,bearing 17 and link bar 13, will rotate flap 9 about bearing 11 andincrease its angle of attack relative to the flow stream. At the pointof maximum flap angle, bearing 15 will be at F on its respective arc. Inaddition to a rotating movement about bearing 11, flap 9 will undergo atranslational movement relative to bearing 5, as bearing 1], couplingflap 9 to foil 7 is moved from A to F on its respective arc. Movement ofactuator arm 31 and coupling 19, in addition to changing angle of attackof foil 7 produces a concurrent change in the angle of attack of flap 9.Contraction of actuator arm 31 also produces a rotational movement ofbell crank 21 about bearing 23 and a translational movement of bearings23 and 25 from position A on their respective arcs to F. As bearings 23and 25 are moved through their respective arcs, the line connectingbearing 23, hearing 25 and bearing 29 will approach a straight line asshown in FIG. 2 and the actuators mechanical advantage proportional tothe linear distance between points 23 and 29 will increase to a maximum,the mechanical advantage on the flap 9 and between points 23 and 15decreases as the actuator arm 31 is contracted. When the bearings are inposition F on their respective arcs, the angle of attack of flap andfoil to the flow stream will be a maximum 1r. At this point themechanical advantage of the actuator on the foil is maximum, matchingthe large hinge moment necessary to overcome the resultant force of thecenter of pressure acting on the flap and foil.

An additional benefit from this invention is realized in a seasituation, where small movements of the foil are required'to compensatefor wave effects. A small movement of the actuator produces a largechange in lift coefficient resulting from the combined change of flapand foil angle. Hydraulic power requirements for the flap and foilcombination are less than for a foil and flap separately actuated. Inthe case of this invention, no separate control is required as flapcontrol is effected through the action of the single actuator 33combining the movement of the foil with the movement of the flap. Thesingle actuator for moving the flapping foil also reduces drag as a needfor separate flap actuator is eliminated.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

What is claimed is:

l. A control system for changing the angle of attack of a hydrofoilhaving a flap pivotally mounted to the hydrofoil, comprising:

a strut pivotally mounted for supporting the hydrofoil and flap;

an actuator;

a bell crank pivotally connected to said actuator, to the strut and tothe flap for changing the foil and flap angle of attack in response tomovement of the actuator;

a support strap pivotally mounted at one end and pivotally connected tosaid bell crank at its other end; and

said actuator having a mechanical advantage for changing the foil angleof attack proportional to the linear distance between the axis ofpivoting movement of the bell crank about the strut and the strap mountpivot axis.

2. A control system for changing the angle of attack of a foil and aflap pivotally mounted to the hydrofoil comprising:

a strut pivotally mounted for supporting the foil;

an actuator;

a link bar pivotally connected to said flap at one end and pivotallyconnected to said actuator at its other end;

a bell crank pivotally connected to said link and said actuator at afirst point and pivotally connected to said strut at a second point;

a support strap mounted for pivotal movement at one end and connected toa third point on said bell crank, for supporting said bell crank andsaid strut; and

said actuator having a mechanical advantage for changing the angle ofattack of said foil proportional to the linear distance between saidsecond pivotal point on said bell crank and said support strap mountpivot axis.

3. The system according to claim 2 wherein movement of said actuator ina first direction increases the angle of attack of the foil andincreases said linear distance.

4. The system according to claim 3 wherein the angle of attack of saidflap is changed coincidentally with the change in the angle of attack ofsaid foil and in the same direction rela tive to the Flow Stream.

5. The system according to claim 2 wherein said actuator has amechanical advantage for changing the angle of attack of said flapportional to the linear distance between said second pivotal point onsaid bellcrank and said link bar pivotal connection point to said flap.

6. A hydrofoil control system comprising:

a hydrofoil;

a flap pivotally mounted to said hydrofoil;

a support strut pivotally mounted and supporting said hydrofoil;

an actuator;

a link bar pivotally mounted to said flap at one end and pivotallymounted to said actuator at its other end;

a bell crank being pivotally mounted to said link bar and said actuatorat a first point, and being pivotally mounted to said support strut at asecond point;

a support strap pivotally mounted at one end and pivotally connected toa third point of said bell crank at its other end;

said first point on said bell crank being intermediate said second pointon said bell crank and the axis of pivoting movement of said supportstrut;

said actuator having a mechanical advantage for changing the angle ofattack of the hydrofoil proportional to the linear distance between saidsecond pivotal point on said bell crank and the strap mount pivot axis;and

said actuator having a mechanical advantage for changing the angle ofattack of said flap proportional to the linear distance between saidsecond pivotal point on said bell crank and said link bar pivotalconnection point to said flap.

1. A control system for changing the angle of attack of a hydrofoilhaving a flap pivotally mounted to the hydrofoil, comprising: a strutpivotally mounted for supporting the hydrofoil and flap; an actuator; abell crank pivotally connected to said actuator, to the strut and to theflap for changing the foil and flap angle of attack in response tomovement of the actuator; a support strap pivotally mounted at one endand pivotally connected to said bell crank at its other end; and saidactuator having a mechanical advantage for changing the foil angle ofattack proportional to the linear distance between the axis of pivotingmovement of the bell crank about the strut and the strap mount pivotaxis.
 2. A control system for changing the angle of attack of a foil anda flap pivotally mounted to the hydrofoil comprising: a strut pivotallymounted for supporting the foil; an actuator; a link bar pivotallyconnected to said flap at one end and pivotally connected to saidactuator at its other end; a bell crank pivotally connected to said linkand said actuator at a first point and pivotally connected to said strutat a second point; a support strap mounted for pivotal movement at oneend and connected to a third point on said bell crank, for supportingsaid bell crank and said strut; and said actuator having a mechanicaladvantage for changing the angle of attack of said foil proportional tothe linear distance between said second pivotal point on said bell crankand said support strap mount pivot axis.
 3. The system according toclaim 2 wherein movement of said actuator in a first direction increasesthe angle of attack of the foil and increases said linear distance. 4.The system according to claim 3 wherein the angle of attack of said flapis changed coincidentally with the change in the angle of attack of saidfoil and in the same direction relative to the Flow Stream.
 5. Thesystem according to claim 2 wherein said actUator has a mechanicaladvantage for changing the angle of attack of said flap portional to thelinear distance between said second pivotal point on said bellcrank andsaid link bar pivotal connection point to said flap.
 6. A hydrofoilcontrol system comprising: a hydrofoil; a flap pivotally mounted to saidhydrofoil; a support strut pivotally mounted and supporting saidhydrofoil; an actuator; a link bar pivotally mounted to said flap at oneend and pivotally mounted to said actuator at its other end; a bellcrank being pivotally mounted to said link bar and said actuator at afirst point, and being pivotally mounted to said support strut at asecond point; a support strap pivotally mounted at one end and pivotallyconnected to a third point of said bell crank at its other end; saidfirst point on said bell crank being intermediate said second point onsaid bell crank and the axis of pivoting movement of said support strut;said actuator having a mechanical advantage for changing the angle ofattack of the hydrofoil proportional to the linear distance between saidsecond pivotal point on said bell crank and the strap mount pivot axis;and said actuator having a mechanical advantage for changing the angleof attack of said flap proportional to the linear distance between saidsecond pivotal point on said bell crank and said link bar pivotalconnection point to said flap.